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УДК 528.482
ПРОБЛЕМЫ ИНЖЕНЕРНОЙ ГЕОДЕЗИИ ПРИ СТРОИТЕЛЬСТВЕ НЕБОСКРЕБОВ. ГЕОДЕЗИЧЕСКИЕ РАБОТЫ ПРИ СТРОИТЕЛЬСТВЕ ВЫСОТНЫХ БАШЕН И МОНИТОРИНГ НЕБОСКРЕБОВ-БЛИЗНЕЦОВ - БАШНИ ЛАМАР В ДЖИДДЕ, САУДОВСКАЯ АРАВИЯ
Кадмос Хатиб
Компания Drake & Scull International PJSC, Саудовская Аравия, г. Джидда, P. O. Box 116806, начальник отдела геодезического мониторинга, тел. +966503419485, +9613911187, e-mail: [email protected], [email protected]
Башня Халифа (Бурдж-Халифа) - это самое высокий небоскреб в мире и ее высота достигает 880 м. Ее открытие состоялось в 2010 году в Дубаи, и она стала первым сооружением для проведения полного комплекса инженерно-геодезических работ во время строительства и последующего его геомониторинга в процессе эксплуатации. К сожалению, не у всех последующих небоскребов имеются такие условия, как у Башни Халифа. Примером тому небоскребы-близнецы - Башни Ламар в Джидда, Саудовская Аравия, где геодезисты впервые столкнулись со многими неожиданными проблемами, для решения которых потребовалась разработка совершенно новой технологии и программного обеспечения. Эта технология включает в себя применение высокоточного электронного тахеометра с набором различных инструментальных средств, обеспечивает минимальный объем вычислений, высокую точность в пределах 5 мм на 1 000 м, реализуется намного быстрее по сравнению с существующими методами, легко совместима с датчиками угла наклона и используется для геомониторинга в режиме реального времени. Традиционная геодезия в сочетании с новой технологией.
Ключевые слова: встроенное приложение Zenith line, мобильный электронный тахеометр TM30, Nivel сенсор, точный инклинометр, уравнивание методом наименьших квадратов, совместная обработка данных, скульптурная башня, сверхвысотный небоскреб, смещение и осадки, Leica Geosystems.
SURVEYING ENGINEERING CHALLENGES IN THE CONSTRUCTION OF SKYSCRAPERS. HIGH RISE TOWER SURVEY AND MONITORING ON LAMAR TWINS BUILDING IN JEDDAH, KSA
Kadmous Khatib
Drake & Scull International PJSC Company, Saudi Arabia, Jeddah, P. O. Box 116806, Chief of Surveying and Monitoring Department tel. +966503419485, +9613911187, e-mail: [email protected], [email protected]
2010 Khalifa Tower (the highest building in the world) 880 meter in Dubai was the reference for all engineering survey and monitoring work in high rise buildings, but unfortunately not all projects have the same condition. 2011 Another challenge at Lamar Towers in Jeddah, Khalifa's survey system does not work well due to conditions of Lamar Towers. New technology with new instruments and tools were created to face the challenge, based on high precision total station, different tools and less calculation, high precision up to 5 mm per 1 000 m, faster more than any method, easy to combine with reading from inclination sensors, used for real time monitoring. Traditional way with new technology.
Key words: Zenith Line, onboard application, TM30 automatic total station, Nivel, precision inclinometer, least squares adjustment, data fusion, sculpted tower, super high-rise, offset and settlement, Leica Geosystems.
INTRODUCTION
The Lamar Towers Project is an important strategic high rise luxury project on the Jeddah Sea Front Corniche. The project consists of 72-floors (305m above ground surface) tower, one 63- floors (285m above ground) tower and one 12- floors podium including retail and office space as well as one 2- floors basement for parking. The basement is 8.4m below ground. The podium is 61m high, which is compreised of 2 level retails and 10 level offices. Podium structure is integrated with both towers.
The proposal for the project was submitted by Cayan in 2008 and was approved in the same year. Construction began in 2008 and, when completed in 2013, Tower 1 will be the tallest building in Jeddah, surpassing the recently completed National Commercial Bank. The development is expected to cost about $ 600 million. The tower was designed by Saudi Diyar Consultants. The Construction Management Service is by Midrar Arabia.The main contractor Drake &Scull construction
Lamar tower has two buildings and each building has two core walls, it is 7 days cycle for one floor construction and Dokka self-climbing form work system is used for the core wall construction. Core walls construct before and the slabs follow after, there are 5 floors height different between them. The core wall is slim and there are 2 tower cranes and 2 placing booms in each core wall so that the space is too narrow to work on the top of them. Also there are further site restrictions.
The feasibility study was carried out to decide what is the best solution for the Lamar tower, The engineer visited the site and collection the field information and it is reported the challenges in surveying works because of the extreme environmental condition such as the weather which is more than 70% humidity and the 50 degree of the temperatures and the construction site conditions is extremely hard for surveyor because of core wall conditions as mentioned above. The small core-wall delivers the other difficulties.
GNSS (Global Navigation Satellite System) solution was primarily proposed to apply active control point concept which is already proved in Burj Khalifa tower in Dubai, 2 GNSS receivers were installed to collect 24-hours GNSS signal and it was analyzed to study the quality of signal and site condition.
It is reported that multipath and cycle slips was over the threshold so that it was decided that GNSS solution was not fit in this site.
1. CONSTRUCTION SURVEY & MONITORING CONCEPT
1.1 Site conditions
Construction Cycles - As all high-rise building in the world the most important things are to achieve to a vertical building closed to the gravity line which make the cladding and the elevator work at the end of the project and keep the huge element at its theoretical center of gravity which will effected if not at (shorting of the columns, sway, settlement , etc.).
Environmental condition - During construction the building exposed to multi conditions which make it move around its center of gravity which we can classified into : -Permanent tilt
This tilt factor drives by the permanent concrete shortening and foundation mat settlement. The permanent tilt value shall be calibrated by long term base.
-Vibration tilt (Elastic) This tilt factor drives by the real time factors such as wind and tower crane, sun radiation, etc. This tilt shall be immediately calibrated during every survey action
Limit of Survey methodology - The normal total station had a limit in transferring points from the ground floor the top because of the angle calculation, refraction of the x-ray, ppm (pair per million, sunlight effect, delaying in time, not easy to see inside the site, not easy to recognized the center of the prism no real time update for the coordinate the top, etc.
Optical and laser plummet had a short limit in height which obliged you to transfer your bench marks to 20 floors max, then close and start new transferring bench marks which make cumulative errors and make your building go out of tilt rang when your building is vibrating also there is no idea what is the verticality situation during work, and big delay in time while the work is going fast.
GNSS technology which is already proved in Burj Khalifa tower in Dubai ,at some site is useless because of tower cranes, placing booms, thin core walls, height of re-bar, etc.
Safety obstruction: During contraction at the high-rise building the most important issue is the safety procedures and tools which give a little limit to move and work such as (safety screen, safety stairs, ect.)
1.2 Setting out Control points
Transfering the offsite Bench Mark to the site and to the corewall is the fundmental survey work in every corewall and slab setting out.
To obtain precise and reliable coordinates that are not influenced by any other environmental condtion and survey technical issue, transfering the ground control coordi-
nates to the top of slab or the top of the existing slab formwork, Lamar tower has unique control point transfer sleeve in every slab that is going through from ground to the top slab. High accurate motorized total station like (TM30) and building survey and monitoring onboard software "Zenith Line onboard application" which is specially developed for high rise core wall alignment application is using to setout corewall and monitoring the periodical building movement and conctrete shortening. The Zenith Line application is used to have direct measurements from the stable ground benchmark through the survey and monitoring sleeves and the surveyor can operate the survey work under the no influence by sun and identical working condtion.
The concept is to set up Automatic Total Station with the onboard Zenith Line application in the same level of the control points (within the plot area of the tower) and transfer the control point coordinates to the working platform on the climbing system with a set of holes in the slab. In the required working slab and where the control points have to be transferred, a special double reflector pole (circular prism at the bottom, 360° reflector at the top) will be set up on the slab hole (along the same line of TPS (Terrestrial Positioning System) telescope by a strut and the coordinate will be obtained at the circular and 360o reflectors (Figure 1).
Figure 1
The terrestrial positioning system shall be precisely turn to the zenith line direction by automatic motorize option aiming to the reflector on working slab. The Zenith Line application will calculate the dX, dY of the bottom circular prism even if the telescope is not aiming to the centre of reflector, "Zenith Line" put the telescope vertical (zenith angle = 0.0000 gon) which will be offset from the reflector and ATR (Auto Target Recognition) is ON.
To determine the final coordinate, the original Control Points coordinates shall be recalculated by the dX, dY from the "Zenith Line" and those value shall be used for the surveyor on the top of the core-wall.
On the top section, three to four Zenith Monitoring Tools (360° - Circular dual reflectors pole) shall be set up at the same time for survey at the top of core wall using onboard Zenith Line application and Zenith Monitoring Tool as in the figure below.
To transfer the coordinates from the ground, it has to occupy the survey hole in proper location where has no obstruction in the vertical sight of view on the concrete slab.
The top slab where is the location to get the coordinates from the ground (Bench Mark) shall be set up by the Zenith Monitoring Tool "Z.M.T." (a special double reflector pole with circular prism at the bottom, 360° reflector at the top) to receive the coordinate in precisely (Figure 2). Three or four (depending on the Core Wall structure, obstacles) sets of Z.M.T. and a total station will be used to determine the precise coordinates of control points that are established on the top concrete slab or slab formwork.
The core walls are being constructed in a sequence of several concrete pours. After each concrete casting the most top slab shall be the location to control the core-wall formworks alignment.
The circle and 360° dual reflectors pole are deployed in good geometry and they are rolled as active control bench marks on the top section.
The total station will observe the geometry of "the circle and 360° dual reflectors pole" by measuring the angles and distances to the 360° reflectors and those information's with the processed at the Control Office or immediately on site and the resulting coordinates applied to the total station to update its coordinates and orientation.
Figure 2
The total station then observes the control points (nails set in the top of the concrete) to derive the corrections to be applied on the formwork structure. These coordinates are in relation to a continuous line of the building as defined by the control lines and therefore when the points are used to set the formwork for the next pour, the construction progresses as a straight element regardless of building movement.
The surveyor has to set up TPS on the or bench mark, the control holes for the survey shall be opened from ground to the top of the slab. TPS orientation, the survey make orientation step for the TPS set up as per building reference frame.
The Zenith Monitoring Tool with Circle and 360° reflectors shall be set up on the top of the concrete slab or the top of the formwork as the receiver from the ground bench mark and the active control points on the core wall.
The surveyor will have to set-up the TPS in a position where he will be able to survey all the marks on the formwork and also some other marks that will be used for other control inside the structure. The tripod will be installed on a very stable place.
1.3 Surveying the control points on the formwork
When the first round of observation will be made, the surveyor will survey the control points on the formwork. He can also survey other marks on the wall and inside the building. Those marks will be used when the surveyor will need to control and set-up other elements in the building. By aiming 3 to 4 marks the surveyor will locate the TPS in the same coordinate frame.
Figure 3
In case there is no line of sight between TPS and the setting out position or it is hard to measure directly, the surveyor shall set 30cm offset line from the concrete beside the core wall as in the below graph (Figure 4).
...........
< \\\ 1 .......
z. _
I
........
..........
Figure 4
Holes in the slabs have to be opened for laser plummet on the working platform on self climbing formwork. Laser plummet has to be used to adjust the corners of the formwork along with the core walls.
2. CONSTRUCTION MONITORING 2.1 Foundation Settlement monitoring
There are 28 settlement monitoring points in B2 level foundation mat. Those are surveyed every day after casting, and a weekly basis, bi weekly, and monthly basis according to the monitoring schedule. The monitoring points are anchored into the foundation mat and securely protected. The first class digital level machine is used for every monitoring survey. The monitoring BM gets from 200m away Off site reference. The site BM for level monitoring is updated in each monitoring sessions. The monitoring programs are categories as the soil foundation work session, and building construction monitoring session. In the soil foundation work session, the survey was carried every day to monitor the dynamic settlement during the earth piling work. In the building construction session, the survey was carried every week in the lower floors, biweeks in the middle floors, and the monthly basis in the high floors. Most of the big settlements was in the beginning and middle height of the building about 510mm each sessions and the value was decreased to 2-3mm after middle and high level. During the Ground Floor to top level construction period, the total amount of the settlements are 5 mm (max), 14mm (min) (Figure 5-6).
Records of settlement at ground floor Tower 1
REFERENCE LEVEL MARK "=" 1.5 10 Nov New point
LOCATION l/po 2/po 3/po 4/po 5/po 6/po 7/po 8/po 9/po 10/po 11/po 12/po TIME DATE
8-M 11-L 11-N 15-M 12-J 15-Q 18-R 17-N 18-J 10-H 7-F 4/J
27TH INSPECTION .+1.496 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1,497 . +1.5 . +1.5 11:00AM 17-Nov-ll
28th INSPECTION .+1.496 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1,497 . +1.5 . +1.5 11:00AM 26-Nov-ll
29th INSPECTION .+1.496 . +1.5 . +1,5 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1.5 . +1,497 . +1.5 . +1.5 11:00AM 03-Dec-ll
30th INSPECTION .+1.495 .+1.498 .+1.498 .+1.498 .+1.498 .+1.499 .+1.497 .+1.497 . +1.5 .+1.497 .+1.495 .+1.499 11:00 AM 31-Dec-ll
31th INSPECTION .+1.495 .+1.498 .+1.498 .+1.498 .+1.498 .+1.499 .+1.497 .+1.497 . +1.5 .+1.497 .+1.495 .+1.499 11:00 AM 08-Jan-12
32nd INSPECTION .+1.495 .+1.498 .+1.498 .+1.498 .+1.498 .+1.498 .+1.497 .+1.497 . +1.5 .+1.497 ,+1.495 .+1.499 11:00AM 15-Jan-12
33 rd INSPECTION .+1.495 .+1.498 .+1.498 .+1.498 .+1.498 .+1.498 .+1.497 .+1.497 . +1.5 .+1.497 .+1-495 .+1.499 11:00AM 22 Jan 12
34th INSPECTION .+1.495 .+1.499 .+1.498 .+1.498 .+1.499 .+1.499 .+1.499 .+1.498 . +1.5 .+1.497 .+1.494 .+1.498 11:00AM 28 Jan-12
35th INSPECTION .+1.494 .+1.499 .+1.498 .+1.498 .+1.499 .+1.499 .+1.499 .+1.498 .+1.499 .+1.497 .+1,494 .+1.498 11:00AM 05-Feb-12
36th INSPECTION .+1.494 .+1.499 Erased .+1.498 .+1.498 .+ 1.499 .+1.499 .+1.498 .+1.499 .+1.497 .+1.494 .+ 1.498 11:00 AM 22-Feb-12
37th INSPECTION .+1.493 ,+1.498 Erased .+1.498 .+1.497 .+ 1.499 .+1.498 .+1.497 .+1.499 .+1.496 .+1,493 .+ 1.497 11:00AM 05-Mar-12
38th INSPECTION .+1.493 .+1.497 Erased .+1.498 .+1.497 .+1.499 .+1.498 .+1.497 .+1.498 .+1.495 .+1-493 .+1.497 11:00AM 27-Mar-12
39th INSPECTION .+1.493 .+1.497 N.A .+1.497 .+1.496 .+1.499 .+1.498 .+1.497 .+1.498 .+1.495 +1,493 .+1.497 11:00AM 05-May-12
40th INSPECTION .+1.493 .+1.497 N.A .+1.497 .+1.496 .+1.499 .+1.498 .+1.497 .+1.497 .+1.496 .+1,493 -+1.497 3:15PM 24-Jun-12
41st INSPECTION .+1.493 .+1.497 N.A .+1.497 .+1.496 .+1.499 .+1.498 .+1.496 .+1.497 .+1.496 .+1,493 -+1.497
POINTS NUMBER ON THE ATTACHED PLAN PO - PODIUM AREA
Figure 5
These points were chosen at the vertex and centre of each separated raft according to the designer requirement.
5/Cp
3/Cp
• W»
:
4/Cp
11 Ipo
•» cö" o J"l2/po
O 6/T2
4/T2
n « ■'/■ °
¿J t 5/T2
1 0/po,
a?
2;p
3/p
Figure 6
8/p.
6/pc!
Í0-
9/po
1 •
7/po
'5?
2.2 Structure vertical shortening monitoring
The construction the core wall and the columns to the adjustd theoretical floor elevations is referenced to the off-site bench mark, and additional compensation corrrections are applied in every floors' construction and the correction shall be made over and above the adjustement it is required to meet design elevation. The compensation corrections are based on the short and long-term effects of the combined structural elements. The concrete shortning is regulary surveyed by the EDM through the survey sleeve.
2.3 Building tilt monitoring
The two core walls are under monitoring by networked inclinometer system connected to the computer to detect dynamic building tilt movement and long term periodical permanent structural tilt. The monitoring epoch is every 15 seconds interval and the movement of the two towers was monitored 24/7 to detect the permanent and temporary tilt (Figure 7).
inclination sensor was installed every 15 floor at an equal interval height and connected to each other to reached to a logging file which record in real time the inclination angle between the sensor 24/7.
Figure 7
Data from the logging file were studied day by day and generate a graph to calculate the displacement dx and dy of the building during survey work to correct the offset by shifting of the coordinate at the drawing according to the results
Using the measurements from the Precise Inclinometers it is then possible to adjust the offsets from the reference control points to the true formwork location.
The basis behind the use of the precise inclinometers data is to measure the rotation of the building in an X-Y direction, i.e. (East - North). It is essential that each Nivel sensor was orientated in the same direction and during installation a series of calibration measurements are taken to synchronize the tilt sensor readings with real position of the building attitude.
At each sensor location an X-Y offset is measured, through determination of the measured tilt and the distance above the rotation center. It is then possible to project the offset to the desired height, i.e. building top.
The below graphs are the plot of Nivel data in the X & Y direction. The average value of this data for a certain time will describe the tilt and verticality of the tower. The tilt in the X and Y directions for the tower can be adopted in the setting out of the core wall to construct the tower in a vertical position (Figure 8-10)
Average
Average
04-03-12
05-03-12
13-08-12
14-03-12
0.17468 0.172366
0.17300 0.17700
0.170 0.163
0.175 0.172
0.536828 0.537254
0.54100 0.54100
0.534 0.535
0.537 0.537
| monthly report
V V* V
J* ./ JT J P ci>
V >" :v ¥ <?* &
30-07-12 19-09-12
0.16904 0.1S5593
0.538145 0.51589
Monthly report of inclination
Figure 8
Yearly report for inclination
Figure 9
Data in real time view
Figure 10
Conclusiton
Due to the development of the technology, building height and size are going to be tall and big, and it is expected the new challeges such as the method of the construction procedure and selection of the new matterial, and the survey and monitoring method could be discussed and studied. In terms of the survey and monitoring of the highrise building construction, the movement of the structure in the high rise level could be more dynamic and difficult to handle during the construciton and the precise and accurate understaing of the building structrue movement is mendatory to carry out proper structure compensation program to build the structure in the tolerance of the design and systematic management of the construction history. Systematic management of the survey and monitoring data, reporting, and the new survey and monitoring technolgoy can help to develop the smooth and well organized working procedure, the reference documatation to manage the conflict between the cooperation of the many companies and the accurate and reliable survey and monitorng result in the project.
© Kadmous Khatib, 2016
